When walking or running without any additional loads, calorie burn can be accurately and robustly predicted from mechanics (e.g., gait speed and terrain incline). Speed and incline can be sensed using accelerometer, barometer, and GPS signals. However, if there are any additional loads that cannot be observed with these sensors (such as treadmill incline, a backpack, a heavy stroller, or inefficient movement patterns due to pathology) or if one of these sensors is not available (e.g., a user does not have a barometric sensor or is on an inclined treadmill where elevation is not actually changing with incline) then estimation of calories burn will be inaccurate.